The fan units are a single object; there is not consumer-replacement parts with the fan module. The entire triple fan unit would need to be replaced.
Warranty should cover any part of the cooler, including the fans.
The fans themselves are variants of the ML120 RGB fans that you can find on nearly all Cooler Master cooling products. Fan curves are managed by motherboard PWM, fan controller or any other controls you might have. There is not a method for managing PWM fan curves with the boxed cooler.
RGB color is managed by the included RGB control module, or can be integrated into your motherboard or other 4-pin RGB controls. Cooler Master does not include a software suite that manages this.
Current fan modules that I am aware of are 2x120mm and 3x120mm. There could easily be potential for 2x140mm modules for 280mm coolers, but uncertain whether these will be available or not.